The present invention relates to leak detection apparatus for blister packs, particularly but not exclusively pharmaceutical blister packs.
Currently, there are a number of methods used to detect leaks in the pockets of pharmaceutical blister packs. In one current method, a vacuum is applied across the blister pack being tested, and the rate of decompression when the vacuum is released gives an overall indication of the existence of a leak in one or more of the pockets of the blister pack. However, this method does not identify which pocket is faulty. In a second current method, individual apparatus is contacted with every pocket of a blister pack for individual testing. Whilst this will reveal individual pockets which are leaking, the overall testing procedure is time-consuming, difficult to validate, marks the pack, expensive, and limited in use.
Identification of which pocket or pockets are leaking in a blister pack is particularly desired in order to provide information on any faults or weaknesses in the manufacturing process, e.g. a fault which constantly leads to the same-positioned pocket being damaged.
According to one aspect of the present invention, there is provided apparatus for detecting a leak in one or more pockets of one or more blister packs, the apparatus comprising means to support the or each pack, means to apply a reduced pressure around the or each pack so as to cause deflection of at least one side of the or each blister pocket, a scanner means moveable or stationary in relation to the blister pockets, and a computing means, wherein the scanner means is able to scan across at least one side of the or each blister pocket so as to detect the deflection of that side of the or each blister pocket at a reduced pressure, and the computing means is able to compare scans at different pressures over the or each pocket.
Means for supporting one or more blister packs and means for creating and releasing a reduced pressure, such as a vacuum, therearound are well known in the art.
The scanner means may be any suitable means able to provide a height or distance scan. Suitable scanner means include lasers, cameras, etc. These scanner means avoid any pocket contact.
The apparatus preferably detects the deflection of the pocket(s) at more than one pressure, e.g. at atmospheric pressure, at a vacuum or near-vacuum, and possibly one or more intermediate pressures.
The scanner means could be stationary or have movement to range across the pockets. In one embodiment, the scanner means is a stationary camera able to scan all blister pockets, whether stationary or mobile themselves, thereunder. There could be more than one scanner, e.g. two scanner means, one on each side of a blister pocket.
The apparatus of the present invention can detect a leak in any format of blister pocket regardless of the shape of the pocket or whether the contents are tablets or capsules. Preferably, the blister packs are supported on a nest or similar means housed in or by the support means. Different nests could be provided for different sized and/or shaped blister packs.
The apparatus of the present invention can be of any suitable size, shape and design so as to be able to test one or a number of blister packs simultaneously.
The apparatus may include means to mark the or each pocket and/or pack having a detected leak.
The apparatus of the present invention is capable of detecting holes of low sizes typically down to five microns, or lower with time to allow pressure changes to be affected in a pocket.
According to a second aspect of the present invention, there is provided a method of detecting a leak in one or more blister pockets of one or more blister packs, comprising the steps of:
(a) locating the or each blister pack on a support means;
(b) applying a reduced pressure around the or each blister pack;
(c) guiding one or more scanner means across at least one side of the or each blister pocket;
(d) changing the pressure; and
(e) detecting the deflection of the or each side of the or each blister pocket so as to determine the presence of a leak in the or each pocket.
According to a third aspect of the present invention, there is provided a monitor screen presentation diagrammatically representing one or more blister packs having one or more blister pockets undergoing a leak detection test, wherein the or each sealed blister pocket is represented by a first indicia, such as a first colour, and the or each leaking pocket is represented in a second indicia, such as a second colour.
One such indicia is the word xe2x80x9cfailxe2x80x9d. With colour, preferably the first colour is green and the second colour is red, although any two suitable colours can be selected. Preferably the or each pack is undergoing a leak detection test using the apparatus and/or method hereinbefore described.
The screen presentation provides clear graphic display of test results for a non-skilled operator. Results can also be recorded or transmitted as desired or necessary.
Table 1 compares apparatus of the present invention identified as xe2x80x9cBlisterScanxe2x80x9d with other prior art test methods.